410 
PACIFIC SCIENCE, VoL XXI, July 1967 
TABLE 6 
Comparison of Some 
Muscle 
Constituents 
of Some 
Marine 
Teleosts 1 
fish 
Na 
K 
Cl 
Ca 
Mg 
REFERENCE 
Muraena helena (eel) 
25.0 
165 
23.7 
18.7 
14.9 
Robertson (i960) 
Mycteroperca bonaci (grouper) 
51.5 
125.5 
26.7 
Becker et al. (1958) 
Scomberomorus maculatus (mackerel) 
71.7 
153.5 
53.8 
Becker et al. (1958) 
Clupea pilchardus (herring) 
Katsuwonus pelamis (skipjack) 
53.8 
170.6 
65.6 
152.1 
51.3 
Carteni and Aloj (1934) 
Red muscle 
35.46 
136.36 
67.06 
3.15 
28.92 
authors (1967) 
White muscle 
20.77 
191.61 
67.71 
8.88 
44.43 
1 Values in mEq/kg water. 
The plasma sodium content of the skipjack 
is greater than those of the Atlantic eel, the 
goosefish, and the kelp bass, but is lower than 
those of the Roman eel, the barracuda, and the 
grouper. The same order is found for the skip- 
jack when the chloride values are compared. 
In comparing the potassium values, the Atlantic 
eel and the barracuda have similar concentra- 
tions of plasma chlorides. The Roman eel, the 
goosefish, and the kelp bass have lower plasma 
chlorides than the skipjack. In K. pel amis, 
lesser concentrations of plasma sodium, potas- 
sium, and chloride are probably due to dif- 
ferences in the osmoregulatory mechanism and 
the type of integument. Excluding the mackerel 
and possibly the barracuda, the listed teleosts 
are not true pelagic species and may be sub- 
jected to some degree of salinity fluctuations. 
In Hawaii, the barracuda is frequently seen in 
shallow lagoons which are subjected to dilu- 
tions during heavy rains. 
Comparison of the plasma calcium of the 
listed teleosts shows that only the goosefish 
(Brull and Cuypers, 1955) had a higher plasma 
content. The value reported by Robertson 
(1954) appears to be in agreement with those 
reported by the other investigators. It is also 
apparent that the plasma magnesium of 
Lophius is greater than those reported by the 
other authors. It is known that temperature 
plays an important role in the solubility product 
constant of compounds and, thus, the rate of 
ionic exchange in apatite. A higher body tem- 
perature coupled with high serum alkaline phos- 
phatase activity and other factors would favor 
a decrease in blood calcium, phosphate, and 
magnesium. It has been reported that tunas 
and skipjacks have body temperatures 6°— 12°C 
higher than their environment (Kishinouye, 
1923; Berg, 1940; Morrow and Mauro, 1950; 
and Van Oosten, 1957). It would be expected, 
then, that the blood calcium and magnesium 
content of the skipjack would be less than that 
found in the colder poikilothermic fishes, but 
greater than that found in mammals. This is 
apparent for the magnesium values but not for 
those of the plasma calcium. Also, there is a 
correlation between the activity of species and 
the amount of plasma magnesium. The more 
active forms generally have lesser concentra- 
tions of plasma magnesium. The greater blood 
calcium level of the skipjack, excluding the 
value of Brull and Cuypers, may be due to the 
intrinsic factors controlling osteogenesis and 
the amount of apatite coupled with the effi- 
ciency of the kidney, the ionic strength of the 
serum, and the amount of vitamins A and D 
stored in the liver. 
In brief, the differences in blood ionic con- 
centrations of various fishes is greatly influenced |i 
by the type and composition of the skeleton. 
Apatite not only stores Ca+ 2 and P0 4 ~ 2 but 
also Na+, Mg+ 2 , and C0 3 -2 . The regulation 
of K+ and Cl - is influenced not by the skele- 
ton but by the gills and kidneys. Osmoregu- 
lation is delicately controlled by enzymes, hor- 
mones, and vitamins. The amounts and activities 
of these complexes are influenced by intrinsic 
and extrinsic factors which affect cell perme- 
ability and metabolism in such a way that each 
organism is unique in its electrolyte compo- 
sition. 
Comparative values of some muscle electro- 
lytes of marine teleosts are presented in Table 
6. The ionic composition of the plasma defi- 
nitely influences that of the surrounding tissues. 
